/Engine/Source/Runtime/Engine/Classes/GameFramework/CharacterMovementComponent.h
Compute a vector of movement, given a delta and a hit result of the surface we are on.
If on a walkable surface, this returns a vector that moves parallel to the surface. The magnitude may be scaled if bMaintainHorizontalGroundVelocity is true. If a ramp vector can't be computed, this will just return Delta.
virtual FVector ComputeGroundMovementDelta ( const FVector & Delta, const [FHitResult](API\Runtime\Engine\Engine\FHitResult) & RampHit, const bool bHitFromLineTrace ) const